K. Mazurek

Macroscopic properties of nuclei according to relativistic mean field theory

Self-consistent calculations within the relativistic mean field theory (RMFT) were performed for 150 spherical even-even nuclei. The macroscopic part of the binding energy was evaluated by subtracting the Strutinsky shell corrections from the RMFT energy. The parameters of a liquid-drop (LD), like mass formula which approximates the RMFT results, were determined. The mass and isospin dependence of the RMFT mean-square radii constant for the neutron, proton, charge and total density distributions were estimated. The RMFT liquid-drop parameters and the radii constants are compared with similar results obtained with the Hartree-Fock-Bogoliubov calculations with the Gogny force (HFB+Gogny) and phenomenological models.

Spectroscopic criteria for identification of nuclear tetrahedral and octahedral symmetries: Illustration on a rare earth nucleus

We formulate criteria for identification of the nuclear tetrahedral and octahedral symmetries and illustrate for the first time their possible realization in a rare earth nucleus Sm152. We use realistic nuclear mean-field theory calculations with the phenomenological macroscopic-microscopic method, the Gogny-Hartree-Fock-Bogoliubov approach, and general point-group theory considerations to guide the experimental identification method as illustrated on published experimental data. Following group theory the examined symmetries imply the existence of exotic rotational bands on whose properties the spectroscopic identification criteria are based. These bands may contain simultaneously states of even and odd spins, of both parities and parity doublets at well-defined spins. In the exact-symmetry limit those bands involve no E2 transitions. We show that coexistence of tetrahedral and octahedral deformations is essential when calculating the corresponding energy minima and surrounding barriers, and that it has a characteristic impact on the rotational bands. The symmetries in question imply the existence of long-lived shape isomers and, possibly, new waiting point nuclei—impacting the nucleosynthesis processes in astrophysics—and an existence of 16-fold degenerate particle-hole excitations. Specifically designed experiments which aim at strengthening the identification arguments are briefly discussed.

N/Z effect on reaction mechanisms cross sections in the

Nuclear reactions between medium-mass nuclei at low energy are characterized by the competition between binary and evaporation process in the compound nucleus de-excitation. A study of the influence of the neutron richness of the entrance channel on the decay paths of the compound nuclei formed in the (78) Kr +(40) Ca and (86) Kr +(48) Ca at 10 MeV/A is presented. The experiment has been performed at Laboratori Nazionali del Sud by using the CHIMERA 4π multidetector for charged particles. The Kinematical characteristics of the two reactions support the conclusion of a production via long lived system. Besides the results relative to the n-poor system are compared to those obtained at GANIL, performed at 5.5 AMeV, in order to study the energy influence.

^{78}Kr+^{40}Ca

M. Krzysieka, M. Kmiecika, A. Maja, P. Bednarczyka A. Braccob,c, F.C.L. Crespib,c, E.G. Lanzad, R. Avigob,c D. Bazzaccoe, G. Benzonib, B. Birkenbachf , N. Blasib S. Bottonib,c, F. Camerab,c, S. Cerutib,c, M. Ciemałaa G. De Angelisg, E. Farneae, A. Gadeah, A. Giazb, A. Görgeni A. Gottardog,j, J. Grębosza, R. Isocratee, S. Leonib,c S. Lunardie,j, K. Mazureka, D. Mengonie,j, C. Michelagnolie,j B. Millionb, A.I. Moralesb,c, D.R. Napolig, R. Nicolinib,c L. Pellegrib,c, F. Recchiae,j, B. Siebeckf , S. Siemi, C. Ure,g,k J.J. Valiente-Dobong, O. Wielandb, M. Zięblińskia

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De-excitation modes of compound systems 118Ba and 134Ba, produced respectively in the 78Kr+40Ca and 86Kr+48Ca collisions at 10 AMeV, are investigated. In particular, the competition among the various disintegration decay paths and the neutron richness dependence of the decay process are studied. Experimentally, the different reaction products were detected and identified with different methods by means of the CHIMERA array at the INFN-Laboratori Nazionali del Sud. Global decay patterns and fragment emission characteristics are presented for the two systems.